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Canopy loading in metric countries

 

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Premier wmw999  (D 6296)

May 6, 2013, 5:19 AM
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Canopy loading in metric countries Can't Post

The title says it -- in the US, we use lbs/sq.ft, which is, of course, meaningless in metric countries. But since most canopies are manufactured by US companies, and sized in sq. ft., does this mean that it's generalized to the rest of the world?

And if so, does that mean that sizes have a more arbitrary feel to jumpers in metric countries?

Mostly curious, but if it means a more arbitrary feel, maybe it's not the best approach

Wendy P.


ABonito  (C License)

May 6, 2013, 5:45 AM
Post #2 of 33 (2953 views)
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Re: [wmw999] Canopy loading in metric countries [In reply to] Can't Post

As canopies are design and sized in sq ft, i use and got used to sq ft to calculate the wingload and everything else like canopy sizes, etc, etc.
I think everyone uses and understands better in sq ft regardless of being in a "metric country".


Premier wmw999  (D 6296)

May 6, 2013, 5:53 AM
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Re: [ABonito] Canopy loading in metric countries [In reply to] Can't Post

That was my thought, too. Just wondering if therefore wing loading is given a little less attention where its calculation isn't a simple matter estimated in about 1/2 second, but instead an arbitrary pain in the ass.

In such a case, "my buddy is using the same canopy and he's not that different a size" sounds a whole lot easier to calculate

Wendy P.


unkulunkulu  (C License)

May 6, 2013, 6:31 AM
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Re: [wmw999] Canopy loading in metric countries [In reply to] Can't Post

Yes, definitely more arbitrary at least at my level at least at our DZ. An instructor recently asked for my weight "in trunks", then said "ok, 170 would do at your experience", I said "thanks, I weighed myself in gear and my exit weight is 99kgs, which is nearly 218 lbs, so I don't want to rush to near 1.3 wingload", he was like "O_o mkay, you have a point". On the other hand I once heard the S&TA said to a visiting jumper "I cannot allow you to jump a canopy at this wingloading at the DZ". So maybe starting at some level they do pay attention to exact numbers.

Buddies mostly don't know their WL and I often have to remind them that they're flying their 170s at approx the same WL as I fly my 190 so they shouldn't tell me how easy it's to land a 170 and how soon I should be jumping the same Crazy

As the sizes of the canopies go, we use sq.ft. everywhere for ram air (yes, rounds that are manufactured in Russia are still in m^2). Won't speak for everyone, but for me yes, 190 is just a number, however now I will convert it and try to remember it in metric system just in case.


(This post was edited by unkulunkulu on May 6, 2013, 7:03 AM)


strife  (D 5457)

May 6, 2013, 7:01 AM
Post #5 of 33 (2884 views)
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Re: [wmw999] Canopy loading in metric countries [In reply to] Can't Post

doesnt feel that way here in oz, in my case it was well covered off in ground school, we where also given a conversion sheet and the wingload \ downsize guide. Also well covered in canopy courses etc.

I think we are generally ok with the metic \ imperial conversions being taught at school, I assume the teach the reverse in the US ?


hcsvader  (E 2952)

May 6, 2013, 7:17 AM
Post #6 of 33 (2868 views)
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Re: [wmw999] Canopy loading in metric countries [In reply to] Can't Post

The conversion to lbs is easy enough to sort out.


excaza  (C License)

May 6, 2013, 7:28 AM
Post #7 of 33 (2852 views)
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Re: [strife] Canopy loading in metric countries [In reply to] Can't Post

In reply to:
I think we are generally ok with the metic \ imperial conversions being taught at school, I assume the teach the reverse in the US ?
A meter is like...a yard, who knows what a kilogram is, my soda comes in liters, and why does the bank say it's 23 degrees out?


alec86  (C 109831)

May 6, 2013, 10:05 AM
Post #8 of 33 (2761 views)
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Re: [excaza] Canopy loading in metric countries [In reply to] Can't Post

why the united states system is retarded Winkhttp://i.imgur.com/huhvM.jpg


Andy9o8  (D License)

May 6, 2013, 10:06 AM
Post #9 of 33 (2760 views)
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Re: [excaza] Canopy loading in metric countries [In reply to] Can't Post

In reply to:
In reply to:
I think we are generally ok with the metic \ imperial conversions being taught at school, I assume the teach the reverse in the US ?
A meter is like...a yard, who knows what a kilogram is, my soda comes in liters, and why does the bank say it's 23 degrees out?

I thought the Rule was 45 degrees.


Premier wmw999  (D 6296)

May 6, 2013, 10:09 AM
Post #10 of 33 (2755 views)
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Re: [alec86] Canopy loading in metric countries [In reply to] Can't Post

Laugh

Wendy P.


popsjumper  (D 999999999)

May 6, 2013, 10:57 AM
Post #11 of 33 (2721 views)
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Re: [alec86] Canopy loading in metric countries [In reply to] Can't Post

In reply to:
why the united states system is retarded Winkhttp://i.imgur.com/huhvM.jpg

I take exception to "retarded".
We are NOT retarded....we are sly devils.

The system we use was built to confuse the rest of the world. It works as designed.
LaughLaughLaugh


Andy9o8  (D License)

May 6, 2013, 11:03 AM
Post #12 of 33 (2716 views)
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Re: [unkulunkulu] Canopy loading in metric countries [In reply to] Can't Post

In reply to:
An instructor recently asked for my weight "in trunks"

Actually, conversion to trunkified weight (a/k/a trunkification) is quite easy. As shown HERE, 1 trunk equals about 140 kg. So let's say you weigh 170 lbs. That converts to about 77 kg., or 0.55 trunk.


rifleman  (Student)

May 6, 2013, 12:48 PM
Post #13 of 33 (2630 views)
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Re: [excaza] Canopy loading in metric countries [In reply to] Can't Post

Simple mnemonics for metric weights and measures:

A metre measures three foot three - it's longer than a yard, you see.

Two and a quarter pounds of jam weigh about a kilogram.

A litre of water's a pint and three quarters


IJskonijn  (A License)

May 6, 2013, 1:46 PM
Post #14 of 33 (2589 views)
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Re: [rifleman] Canopy loading in metric countries [In reply to] Can't Post

It's one of the stupid aspects of skydiving (and aviation in general). Even though we do everything in metric here, skydiving related stuff is still imperial. And yeah, it somewhat works, although I won't be able to tell you the size of my canopy in square meters, nor my wingload in kg/m^2.


unkulunkulu  (C License)

May 6, 2013, 2:07 PM
Post #15 of 33 (2574 views)
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Re: [IJskonijn] Canopy loading in metric countries [In reply to] Can't Post

Quote:
Even though we do everything in metric here, skydiving related stuff is still imperial.
Do you measure altitude in ft?


Premier skydiverek  (C 41769)

May 6, 2013, 2:15 PM
Post #16 of 33 (2564 views)
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Re: [unkulunkulu] Canopy loading in metric countries [In reply to] Can't Post

In reply to:
Quote:
Even though we do everything in metric here, skydiving related stuff is still imperial.
Do you measure altitude in ft?

Nope. 4000 meters it is Cool !


ABonito  (C License)

May 6, 2013, 4:40 PM
Post #17 of 33 (2523 views)
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Re: [skydiverek] Canopy loading in metric countries [In reply to] Can't Post

That's the point, skydiving is all in imperial measurements.
Everyone thinks and talks in ft, lb, etc !! The conversion from kg to lb is easy enough and concerning altitude, well, i myself prefer to think in ft not meters .....


mistercwood  (Student)

May 6, 2013, 6:03 PM
Post #18 of 33 (2495 views)
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Re: [ABonito] Canopy loading in metric countries [In reply to] Can't Post

In reply to:
That's the point, skydiving is all in imperial measurements.
Everyone thinks and talks in ft, lb, etc !! The conversion from kg to lb is easy enough and concerning altitude, well, i myself prefer to think in ft not meters .....

Exactly. I can jump at 14000ft, or 4000m. Why would I cheat myself out of all that extra freefall time? Wink


GalFisk  (D 23239)

May 7, 2013, 1:12 AM
Post #19 of 33 (2426 views)
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Re: Canopy loading in metric countries [In reply to] Can't Post

I live in Sweden. We skydive using meters for altitude, while our neighbors in Norway use feet for some reason. It may be that they don't have their own association but are part of Luftsportforbundet (Air Sport Association) and have inherited more from other flying sports than we have in Sweden. Or I may be wrong.
In any case, in both countries we use ft^2 for canopy sizes. In both countries we have a table (one in Sweden, another in Norway) showing the minimum allowed and recommended size (in ft^2) of canopy, with regard to exit weight (in kg) and number of jumps. Because this table exists and is part of our basic rules, wing loading in actual numbers (lbs/ft^2, or kg/m^2 or combinations of the above) are not often calculated or discussed.


ABonito  (C License)

May 7, 2013, 1:40 AM
Post #20 of 33 (2413 views)
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Re: [IJskonijn] Canopy loading in metric countries [In reply to] Can't Post

IJskonijn wrote:
It's one of the stupid aspects of skydiving (and aviation in general). Even though we do everything in metric here, skydiving related stuff is still imperial. And yeah, it somewhat works, although I won't be able to tell you the size of my canopy in square meters, nor my wingload in kg/m^2.

Exactly ... i also cannot tell whats my wingload in kg/mt ... Shocked


potatoman  (Student)

May 7, 2013, 3:07 AM
Post #21 of 33 (2387 views)
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Re: [wmw999] Canopy loading in metric countries [In reply to] Can't Post

Wendy,

Most canopies are in sqfeet. So, it is my weight, plus other weight, x2.2...... The rest is the same.

Not so much of a pain, and we follow wingloading quite well as a rule of thumb.


Jalien  (A License)

May 7, 2013, 3:26 AM
Post #22 of 33 (2380 views)
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Re: [ABonito] Canopy loading in metric countries [In reply to] Can't Post

A quick bit of maths tells me that if you divide your WL in kg/sqm by 5, you'll get near enough your WL in lb/sqft (to within 3%)


holie  (A License)

May 7, 2013, 4:28 AM
Post #23 of 33 (2349 views)
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Re: [Jalien] Canopy loading in metric countries [In reply to] Can't Post

Jalien wrote:
A quick bit of maths tells me that if you divide your WL in kg/sqm by 5, you'll get near enough your WL in lb/sqft (to within 3%)


... but you don't know your canopy in sqm, do you?


mr2mk1g  (C 103449)

May 8, 2013, 3:52 AM
Post #24 of 33 (2236 views)
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Re: [wmw999] Canopy loading in metric countries [In reply to] Can't Post

In the UK everyone's essentially bi-lingual when it comes to measurements as metrification wasn't that long ago, is far from complete and still ongoing on a rolling basis.

The weights and measures we use in everyday life are a complete hodge-podge. We buy petrol in litres but cover distance in miles and then work out our petrol consumption in MPG. Engine sizes are measured in ltrs but power output is in BPH. Milk and beer is still in pints but coke comes in ltrs. We tend to weigh ourselves in stones but bake in lb. and oz. though we buy the ingredients in kgs. We state our height in ft and inches but everything else is measured in metric, except distance in miles and the size of land in acres. Strawberries come by punnet. Ale can be bought by the yard. A pound of gold weighs less than a pound of lead while an ounce of lead weighs less than an ounce of gold. We like to fuck with people.

This means most people are pretty happy converting between two, even switching from one measurement to another on the same task. I might buy 2x4 lumber specifying its length in meters for example.

For wing loading you either know your weight in pounds or convert from stones by multiplying by 14. The size of the canopy in sq ft is happily understood even though we'll pack on a tarp bought in meters squared.

Our botch job of a system (which will probably be fully metric in another 50 years) is probably even more confusing to outsiders than the seemingly random US system. It does mean though that we can use virtually any measurement interchangeably and either convert at will or just mix and match and overlook any incongruity.


DHemer  (B License)

May 11, 2013, 11:39 AM
Post #25 of 33 (2022 views)
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Re: [mr2mk1g] Canopy loading in metric countries [In reply to] Can't Post

SA is a metric country but when it comes to skydiving everything is in feet and lbs

Plus 10000ft sounds more impressive than 3000m to a whuffo

Only time it is an issue is when working out WL i have to think more than I would like to get from kg to lbs


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